This is a nice definition, and I think not understanding this or something like it has made life hard for many GMs; they understand that they are supposed to insure that the game is fun, but the game designers are shy about defining what the object of the game actually is.

So instead of doing what they can to insure that the game is on course, with fun being generated by every participent, they instead think that the fun comes from them, that they are meant to be an exclusive entertainer of players.

When designers are less shy about what they mean by keeping the game fun, particularly the kind of game they aim for, then this problem evaporates.

Obviously other related problems appear, like how easy it is to hold the game to that object, how much the players have to be on board, or even how much they can be on board, and how much the rules contribute to that, and how much leway there is in that object or capacity to transform it into other things. All that stuff. But understanding that you have a role to play in setting up emergent fun is a very basic GMing thing. Without it, quite honestly most of the trappings of an rpg will be a hindrence, at best a comfort blanket.